The invention relates to an air-cleaner installed in the intake system of an internal combustion engine, filtering an intake air, and feeding the filtered air to the engine.
Recent internal combustion engines are further required to prevent leakage of a vaporized fuel from the intake system. Consequently, a technique is spread, which provides an adsorbent adsorbing the vaporized fuel in an air-cleaner installed in the intake system. For example, Japanese Patent Application Laid-Open No. 2002-266713 (referred to as Patent Publication 1) discloses the following air-cleaner. The air-cleaner includes therein an adsorption sheet opposed to a filter element for adsorbing a vaporized fuel, being positioned on a clean side within the housing of the air-cleaner.
Japanese Patent Application Laid-Open No. 2002-276486 discloses an invention related to adsorption means (referred to as Patent Publication 2). The adsorption means disclosed therein is formed by holding granular activated carbon between unwoven fabrics, and integrally putting heat resistant nets on the respective unwoven fabrics. The adsorption means is also arranged to be opposed to a filter element on the clean side in the air-cleaner.
As disclosed in the above patent publications, for preventing the vaporized fuel from leaking from the intake system to the atmosphere, the techniques for adsorbing the vaporized fuel using the air-cleaners have been recently performed.
However, the air-cleaner is a unit mainly intended to filter the intake air and feed the filtered air to the engine. Therefore, while the engine is operated, an intake action produces an air-flow directed from the dust side to the clean side within the air-cleaner.
According to the invention disclosed in the Patent publication 1, the adsorption sheet receives the intake air to be flexible downstream due to the air pressure. If the adsorption sheet is thickened to prevent such a flexing phenomenon, the air-flow resistance is increased.
Furthermore, according to the invention disclosed in the Patent Publication 2, it is disadvantageously difficult to form such different types of materials as the granular activated carbon, the nonwoven fabrics, and the heat resistant nets into an integrated member. Holding of the granular activated carbon between the paired heat resistant nets eventually increases air-low resistance.